Single carrier transmission is an effective method of reducing the peak-to-average power ratio in a power amplifier, and performing communication with highly efficient power. A single-carrier frequency division multiple access (SC-FDMA) method can provide a multiple access to a plurality of users of the single carrier transmission on a frequency domain in multiple-user environment, such as a cellular system, and improve a frequency use efficiency based on a multi-user diversity effect.
With SC-FDMA, it is necessary to allocate continuous radio channels on the frequency domain to allocate radio channels to users who perform communication by way of single carrier transmission. A conventional radio channel allocating method has a problem in which a computation amount becomes enormous according to the number of radio channel groups. Further, there is a problem in which one user is likely to occupy all bands, and therefore it is difficult to obtain the multi-user diversity effect.